In general, in image display devices such as a cathode ray tube display device (CRT), a plasma display (PDP), an electroluminescence display (ELD), and a liquid crystal display device (LCD), for the purpose of preventing a lowering of contrast or reflection of an image due to the reflection of external light, an antireflection film is disposed on the outermost surface of a display so as to reduce a reflectance by using a principle of optical interference.
In general, such an antireflection film can be prepared by forming on a support a low refractive index layer having a refractive index lower than that of the support and having an appropriate thickness. In order to realize a low refractive index, it is desired to use a material having a low refractive index as far as possible for the low refractive index layer.
Also, since the antireflection film is used for the outermost surface of a display, it must have high scar resistance. In a thin film having a thickness of about 100 nm, in order to realize high scar resistance, the film must have strength by itself and adhesiveness to a lower layer.
Also, since the antireflection film is used for the outermost surface of a display device, it is required to have excellent resistance to attachment against various stains centering fingerprints in exhibition or daily use, or even in the case where the film is stained, it is required to have excellent stain wiping properties (the both properties will be hereinafter collectively referred to as “antifouling properties”).
In order to decrease the refractive index of a material, there are measures such as (1) introduction of a fluorine atom and (2) decrease of density (introduction of voids). However, in all of these measures, the film strength or adhesiveness at an interface is lowered so that the scar resistance tends to be lowered. Thus, it was a difficult problem to make low refractive index and high scar resistance compatible with each other.
Also, in order to increase the hardness of a film itself, it is important to make a hardening reaction sufficiently proceed. A method for hardening a low refractive index layer of an antireflection film by making a hydroxyl group of a fluorine-containing polymer react with a hardening agent by the action of an acid catalyst is proposed in Japanese Patent No. 3498381, JP-A-11-189621, JP-A-11-228631, JP-A-2004-307524 and JP-A-2003-26732.
Also, in order to improve antifouling properties, an example of a fluorine-containing polymer having silicon introduced into the polymer principal chain is described in Japanese Patent No. 3498381, JP-A-11-189621, JP-A-11-228631 and JP-A-2004-307524.
On the other hand, JP-A-62-174276, JP-A-1-259071, JP-A-2-173172 and JP-A-2-302477 propose a hardenable composition or a paint using an amine salt of sulfonic acid as a catalyst.